Hiking is the preferred term, for a long, vigorous walk, usually on trails (footpaths), in the countryside, while the word walking is used for shorter, particularly urban walks. It is a popular activity with numerous hiking organizations worldwide, and studies suggest that all forms of walking have health benefits.
Trail running is a sport which consists of running and hiking over trails. It differs from road running and track running in that it generally takes place on hiking trails, often in mountainous terrain, where there can be much larger ascents and descents.